Molecular signature of cardiomyocyte clusters derived from human embryonic stem cells

¹ School of Humanities and Informatics, University of Skövde, SE-541 28 Skövde, Sweden; Dept of Clinical Chemistry/Transfusion Medicine, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden
² Cellartis AB, Arvid Wallgrens Backe 20, SE-413 46 Göteborg, Sweden
³ Dept of Clinical Chemistry/Transfusion Medicine, Sahlgrenska University Hospital, SE-413 45 Göteborg, Sweden
⁴ School of Humanities and Informatics, University of Skövde, SE-541 28 Skövde, Sweden

^* To whom correspondence should be addressed. E-mail: jane.synnergren{at}his.se.

Correspondence may also be addressed to P. Sartipy at peter.sartipy@cellartis.com

	Abstract

Human embryonic stem cells (hESCs) can differentiate in vitro into spontaneously contracting cardiomyocytes (CMs). These cells may prove extremely useful for various applications in basic research, drug discovery, and regenerative medicine. In order to fully utilize the potential of the cells, they need to be extensively characterized and the regulatory mechanisms that control hESC differentiation towards the cardiac lineage need to be better defined. In this study, we employed microarrays to analyze, for the first time, the global gene expression profile of isolated hESC-derived CM clusters. By comparing the clusters with undifferentiated hESCs and using stringent selection criteria, we identified 530 up-regulated and 40 down-regulated genes in the contracting clusters. To further characterize the family of up-regulated genes in the hESC-derived CM clusters, the genes were classified according to their Gene Ontology annotation. The results indicate that the hESC-derived CM clusters display high similarities, on a molecular level, to human heart tissue. Moreover, using the family of up-regulated genes, we created protein interaction maps which revealed topological characteristics. We also searched for cellular pathways among the up-regulated genes in the hESC-derived CM clusters and identified eight significantly up-regulated pathways. Real-time qPCR and immunohistochemical analysis confirmed the expression of a sub-set of the genes identified by the microarrays. Taken together, the results presented here provide a molecular signature of hESC-derived CM clusters, and furthers our understanding of the biological processes which are active in these cells.